Arena told reporters Donovan has opted to come back to the MLS champions for a ninth season after weighing whether to quit and dealing with physical and mental fatigue, the Los Angeles Times reported.
The coach said it wasn't yet determined whether the 30-year-old would report in time for the Galaxy's March 3 season opener against the Chicago Fire.
"I wouldn't want to report that now because we still haven't finalized it," he said. "He just needs a little bit more time off. He's had a couple of years that have taken their toll."
Donovan, who has 92 regular-season career goals with the Galaxy, played 49 games in 48 weeks last year as Los Angeles won its second straight MLS Cup.